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STRSEP(3) Library Functions Manual STRSEP(3)


strsep, stresepseparate strings


Standard C Library (libc, -lc)


#include <string.h>

char *
strsep(char **stringp, const char *delim);

char *
stresep(char **stringp, const char *delim, int escape);


The strsep() function locates, in the nul-terminated string referenced by *stringp, the first occurrence of any character in the string delim (or the terminating ‘\0’ character) and replaces it with a ‘\0’. The location of the next character after the delimiter character (or NULL, if the end of the string was reached) is stored in *stringp. The original value of *stringp is returned.

An “empty” field, i.e., one caused by two adjacent delimiter characters, can be detected by comparing the location referenced by the pointer returned by strsep() to ‘\0’.

If *stringp is initially NULL, strsep() returns NULL. The stresep() function also takes an escape character that allows quoting the delimiter character so that it can be part of the source string.


The following uses strsep() to parse a string, containing tokens delimited by white space, into an argument vector:

char **ap, *argv[10], *inputstring; 
for (ap = argv; ap < &argv[9] && 
    (*ap = strsep(&inputstring, " \t")) != NULL;) { 
	if (**ap != '\0') 


The strsep() function is intended as a replacement for the strtok() function. While the strtok() function should be preferred for portability reasons (it conforms to ANSI X3.159-1989 (“ANSI C89”)) it is unable to handle empty fields, i.e., detect fields delimited by two adjacent delimiter characters, or to be used for more than a single string at a time. The strsep() function first appeared in 4.4BSD.
August 12, 2006 NetBSD 7.0